SWODY1
SPC AC 090557
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1157 PM CST SAT NOV 08 2008
VALID 091200Z - 101200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
RIDGING ALOFT OVER WRN CONUS WILL CONTINUE TO BREAK DOWN AS CYCLONIC
FLOW IS MAINTAINED OVER GREAT LAKES AND NERN CONUS...AND STG
SHORTWAVE TROUGH NOW OVER NRN/CENTRAL CA MOVES OVER 4-CORNERS
REGION. BY 10/12Z...THAT TROUGH WILL PIVOT SEWD THEN EWD ACROSS
SRN/CENTRAL ROCKIES TO ADJACENT HIGH PLAINS. MEANWHILE...MID-UPPER
LEVEL LOW NOW CENTERED OVER LH IS FCST TO BECOME PART OF BINARY
SYSTEM...AS SHORTWAVE TROUGH NOW APCHG MN ARROWHEAD STRENGTHENS INTO
CLOSED LOW AND PIVOTS SEWD/EWD ACROSS GREAT LAKES.
AT SFC...EXPECT WELL-DEFINED CYCLOGENESIS INVOF OK/NM BORDER DURING
LATTER 6-9 HOURS OF PERIOD AS UPPER TROUGH APCHS. LEE TROUGH WILL
EXTEND GENERALLY SSEWD ACROSS TX PANHANDLE AND W-CENTRAL TX. NEARLY
COLLOCATED DRYLINE WILL BECOME BETTER DEFINED WITH TIME...LATE IN
PERIOD...AS LOW LEVEL MOISTURE INCREASES OVER CENTRAL/S TX.
...CENTRAL/SRN PLAINS...
TSTMS FCST TO DEVELOP AFTER DARK ACROSS PORTIONS TX/OK AND PERHAPS
INTO SRN KS...MOST LIKELY AFTER 06Z...AND INCREASING IN COVERAGE
THROUGH END OF PERIOD. MOST INTENSE CELLS OR CLUSTERS MAY PRODUCE
LARGE HAIL...BUT CATEGORICAL OUTLOOK IS PRECLUDED ATTM BY
COMBINATION OF SPATIAL UNCERTAINTIES AND MRGL LEVELS OF FCST
INSTABILITY.
PERSISTENT WAA/MOIST ADVECTION REGIME WILL OCCUR ACROSS MUCH OF
CENTRAL/SRN PLAINS AS UPPER TROUGH PIVOTS EWD THROUGH 4-CORNERS/SRN
ROCKIES REGION. MOIST RETURN-FLOW REGIME WILL BE IMMATURE FOR THIS
PERIOD...LARGELY BECAUSE OF TRAJECTORIES EMANATING FROM CONTINENTAL
RIDGING AND INCOMPLETE AIR MASS MODIFICATION PROCESS OVER NRN GULF.
PRIND 50S F SFC DEW POINTS WILL SPREAD NWD THROUGH CENTRAL TX BY
10/12Z...GRADATING TO MID-UPPER 60S F OVER DEEP S TX. EARLY-STAGE
RETURN MOISTURE WILL BE TRANSPORTED NWD ACROSS NRN TX AND OK LATE IN
PERIOD...PROBABILITIES OF BEING LIFTED ISENTROPICALLY TO LFC
INCREASING WITH EACH PASSING HOUR. LAPSE RATES ALOFT GENERALLY WILL
INCREASE WITH WWD EXTENT...BUT STRONGEST COOLING ALOFT WILL REMAIN
DISPLACED FROM RICHEST LOW LEVEL MOISTURE UNTIL AFTER 10/12Z.
MODIFIED NAM-KF SOUNDINGS SUGGEST ELEVATED MUCAPES 300-500 J/KG ARE
POSSIBLE BY 10/12Z. GIVEN BROAD NATURE OF WAA REGIME AND LACK OF
STRONGLY DEFINED WARM FRONTAL ZONE...MOST PROBABLE MESOSCALE AREAS
FOR CONVECTIVE INITIATION ARE NEBULOUS AND UNCERTAIN.
...TX COASTAL PLAIN...
CONDITIONAL SVR PROBABILITY EXISTS GIVEN FCST OF VERY LARGE LOW
LEVEL HODOGRAPHS OVERNIGHT AND -- IN A FEW MODEL SOUNDINGS --
EFFECTIVE LIFTED PARCELS ROOTED NEAR SFC FOR DEW POINTS MID-UPPER
60S F WITH NARROW BUOYANT PROFILE EXTENDING UPWARD INTO ICING
LAYERS. ATTM...WILL NOT INCLUDE THAT AREA IN SVR PROBABILITIES
BECAUSE OF LACK OF APPARENT FOCI FOR INITIATION.
..EDWARDS/LEVIT.. 11/09/2008
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